Having started from seventh on the grid on the hard tyres, Gasly rose up the order as others pitted, and by lap 44 he was in third place.
Up and down the pitlane, drivers were being told that rain was expected but rather than have Gasly wait for a possible opportunity to switch straight to intermediates, the team called him in for medium tyres just a few laps before the rain hit.
He was thus obliged to make a second stop as the rain intensified and take intermediates on his way to an eventual seventh place.
While he was pleased to see Alpine team-mate Esteban Ocon finish third Gasly admitted that he was frustrated by the way his afternoon unfolded.
"I must say on my race I'm disappointed and confused because when we're running P3 and I'm going green and we know the rain is coming. I was in the perfect position to just stay long," he said when asked by Motorsport.com about the race.
"I called on the radio, I wanted to stay long and benefit from the conditions. And then we boxed, and two laps later the rain came. We need to review why we boxed, because there was P3 and P4 on the table for the team, and it would have been a couple more points.
"But once again I don't want to share too much frustration, it's still a beautiful day for the whole team with the podium but we have a couple of things to improve, and we'll do it for next time."
Gasly admitted that staying on the road in the wet conditions had been very difficult.
"It was exciting," he said. "A couple of big moments, I must say the grip was extremely low. Poor visibility, blue flags, I needed to go between cars and debris here and there.
"The paint [and] a couple of pedestrian crossings were horrendous, so even in fifth gear you had wheelspin up the hill. It was very tricky, but kind of reminded me from last year at the start of the race. It was fun."
Asked if it was dangerous, he said: "I think there was one lap where coming down to Turn 5 it was like 'something bad is going to happen'. It was depending on the part of the track, some areas were drying, and had dry patches, and some others were very, very wet.
"The problem, in this case, is you use the rubber on the dry areas of the track, so you kind of scrub your tyres, and when you get to the very wet areas, it feels like half-slick tyres and it becomes very sketchy.
"I think we did the best job we could, splitting the two Ferraris, but there were at least three positions we could have got with a better call.
"But we'll review that and still a very positive day for the team in terms of performance, the best performance we've shown all year so hopefully we can build up from there."
